A quasiparticle of mass m is trapped by an extended crystaldefect, which has a shape of a narrow, straight tube of length l.The quasiparticle hence is confined to move within this defect.Consider that the tube of this defect is sealed at both ends withpotential V = 0 inside the tube. Treat the defect as a 1D infinitesquare well. Assume that this tube defect is placed at an angle Θrelative to the surface of the earth. The quasiparticle experiencesthe usual gravitational potential V = mgh. Calculate the lowestorder change in the energy of the ground state due to thegravitational potential.
